Pirker, Stefan

Puttinger, Stefan

von Berg, Lukas

English

Engineering Conferences International

Engineering Conferences InternationalECI Digital ArchivesThe 14th International Conference on Fluidization– From Fundamentals to Products Refereed Proceedings2013Identification of Bed Zones and Flow Regimes inSingle and Multiple Spout-Operated Beds byDigital Image Processing and Pressure ProbesStefan PuttingerJohannes Kepler University, AustriaLukas von BergJohannes Kepler University, AustriaStefan PirkerJohannes Kepler University, AustriaFollow this and additional works at: http://dc.engconfintl.org/fluidization_xivPart of the Chemical Engineering CommonsThis Article is brought to you for free and open access by the Refereed Proceedings at ECI Digital Archives. It has been accepted for inclusion in The14th International Conference on Fluidization – From Fundamentals to Products by an authorized administrator of ECI Digital Archives. For moreinformation, please contact franco@bepress.com.Recommended CitationStefan Puttinger, Lukas von Berg, and Stefan Pirker, "Identification of Bed Zones and Flow Regimes in Single and Multiple Spout-Operated Beds by Digital Image Processing and Pressure Probes" in "The 14th International Conference on Fluidization – FromFundamentals to Products", J.A.M. Kuipers, Eindhoven University of Technology R.F. Mudde, Delft University of Technology J.R. vanOmmen, Delft University of Technology N.G. Deen, Eindhoven University of Technology Eds, ECI Symposium Series, (2013).http://dc.engconfintl.org/fluidization_xiv/6IDENTIFICATION OF BED ZONES AND FLOW REGIMES IN SINGLE AND MULTIPLE SPOUT-OPERATED BEDS BY DIGITAL IMAGE PROCESSINGAND PRESSURE PROBES Stefan Puttingera*, Lukas von Berga and Stefan Pirkera aChristian-Doppler Laboratory on Particulate Flow Modelling, Johannes  Kepler University Linz,Altenbergerstraße 69, 4040 Linz, Austria  *T: +43-732-2468-6478; F: +43-732-2468-6462; E: stefan.puttinger@jku.at  Fluidized beds have a huge variety of applications in process industry. As the desired properties of the fluidized bed can strongly vary according to the process it is crucial to have proper knowledge of the flow regimes within the fluidized bed.In typical large scale applications in industry, fluidized beds are operated with one or more spout sections without background fluidization. In such cases it is necessary to minimize dead zonesbetween the spouts to avoid sticking of material in these areas. Spout operated beds also show some mixed regimes (like e.g. spoutswithin a bubbling bed). These mixed regimes might appear only within close borders of superficial velocity or bed height. Therefore, it is helpful to have regime maps (like presented by Link et al. (1)) or correlations to predict the bed behaviour for certain boundary conditions correctly.  Theaim of this experimental study is to identify the different flow regimes and bed zones via digital image processing of high-speed video data and pressure measurements on the bed. Experiments were conducted in a lab-scale 2D bed with a cross-section of 0.15 x 0.02m and different particle diameters of 0.5, 2 and 4mm.  After a general visual classification of the flow regime (Fig. 1), the recorded image sequences were processed in Matlab to identify the different bed zones. Calculating the mean images and pixel variance images allows identification of the dead zones and annular regions for the spout bed regimes (Fig. 3). In the bubbling zones a Lagrangian object tracking (cf. Busciglio et al. (2)) calculates equivalent bubble diameters and bubble rise velocities. In addition, a PIV (particle image velocimetry) cross correlation can calculate particle velocities. The basic idea for all processing steps is that they work equally on experimental images and post-processing images from CFD and CFD-DEM coupled simulations. This provides a good basis for data comparison and evaluation of simulation models. From the pressure drop information the frequencies of spout collapsing or slugging can be extracted via FFT (Fast Fourier Transform). In the case of an internal jet with bubbling bed the bubble eruption frequency can be detected (Fig.2). The observed values for minimum spout velocities and jet penetration length match quite well with correlations from literature (e.g. Bi (3)).    REFERENCES  1. J.M. Link, L. a. Cuypers, N.G. Deen, J. a. M. Kuipers, Flow regimes in a spout–fluid bed: A combined experimental and simulation study, Chemical Engineering Science. 60 (2. A. Busciglio, G. Vella, G. Micale, L. Rizzuti, Analysis of the bubbling behaviour of 2D gas solid fluidized beds Part I. Digital image analysis technique, Chemical Engineering Journal. 140 (2008) 3983. H.T. Bi, A Discussion on Minimum Length, The Canadian Journal of Chemical Engineering. 82 (2004) 4a)  Figure 2: Bed zones in spoutThe blue line marks the static bed height, the magenta linesidentify the spoutregionsand the yellowand red lines mark the dead zones via square andlinearinterpolation.  Figure 1: Regime map for 2mm particles.2005) 3425–3442. –413.Spout Velocity and Jet Penetration   b)    -bed regime for a) 0.5mm, b) 2mm and c) 4mm particles.   Figure 2: Fouriertransform of pressuresignals. –10.  c)   

Identification of Bed Zones and Flow Regimes in Single and Multiple Spout-Operated Beds by Digital Image Processing and Pressure Probes

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Identification of Bed Zones and Flow Regimes in Single and Multiple Spout-Operated Beds by Digital Image Processing and Pressure Probes

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